package cn.edu.jxnu.practice;

/**
 * @description 给定一个数组A[0,1,...,n-1],请构建一个数组B[0,1,...,n-1],其中B中的元素
 * B[i]=A[0]*A[1]*...*A[i-1]*A[i+1]*...*A[n-1]。不能使用除法。
 * 
 * 
 *  //B[i]=A[0]*A[1]*...*A[i-1]*A[i+1]*...*A[n-1]
	//从左到右算 B[i]=A[0]*A[1]*...*A[i-1]
	//从右到左算B[i]*=A[i+1]*...*A[n-1]
 * @author Mr.Li
 *
 */
public class Multiply {

	public int[] multiply(int[] A) {
		int length = A.length;
		int[] B = new int[length];
		if (length != 0) {
			B[0] = 1;
			// 计算下三角连乘
			for (int i = 1; i < length; i++) {
				B[i] = B[i - 1] * A[i - 1];
			}
			int temp = 1;
			// 计算上三角
			for (int j = length - 2; j >= 0; j--) {
				temp *= A[j + 1];
				B[j] *= temp;
			}
		}
		return B;
	}
}